Bug#983035: Missing dependency on dbus-x11

[Francesco P. Lovergine]

Package: xfce4
Version: 4.16
Severity: normal

I found a missing dependency on /usr/bin/dbus-launch (dbus-x11) in bullseye, somewhere.
Not sure this is an xfce4 issue specifically, feel free to reassign to another proper package.

In order to replicate the problem: I just installed from scratch a bullseye current image
(debian/testing64) in vagrant, with virtualbox provider, an upgraded it. Then
installed xfce4i (the metapackage) and started lightdm. After that, the user
cannot login and start a session due to missing dbus-launch, with appropriate
message at screen. Installing dbus-x11 solves the problem.

-cheers

--
Francesco P. Lovergine

[Trent W. Buck]

Francesco,

Is dbus-user-session installed?
xfce4-session recommends dbus-user-session, so
it SHOULD already be installed.

dbus-launch (from "dbus-x11") package is the Old Way,
which is still attempted as a fallback.

Most systemd linux systems will instead use libpam-systemd to set up the user dbus session.
In this case, dbus-launch is not used.

You can see this in the source code -- if there's already a dbus
session (usually created by systemd), it just returns immediately.

https://sources.debian.org/src/xfce4-session/4.16.0-1/xfce4-session/main.c/#L275-L278

This is encoded in the control file like this:

https://sources.debian.org/src/xfce4-session/4.16.0-1/debian/control/#L31

On a Debian GNU/Linux architecture, that
will default to the systemd path (dbus-user-session).
Where systemd isn't available (e.g. Debian GNU/kFreeBSD),
it falls back to dbus-x11 (dbus-launch).

See also

https://sources.debian.org/src/xfce4-session/4.16.0-1/debian/changelog/#L37-L38
https://bugs.debian.org/836062

[Francesco Paolo Lovergine]

On Thu, Jan 13, 2022 at 05:06:29PM +1100, Trent W. Buck wrote:
>Francesco,
>
>Is dbus-user-session installed?
>xfce4-session recommends dbus-user-session, so
>it SHOULD already be installed.
>

As explained this is a bug found casually while using testing64, at the stage
of its development in that date, by installing xfce4 (the meta-package) after
a base system installation (i.e. without any desktop task installed).

I have no idea if currently this isssue is still present, but I think
it could be reproduced as detailed, something I could eventually try again
in a nearest future.

-cheers

--
Francesco P. Lovergine